A typical liquid crystal display cell comprises two glass slides spaced about 12 .mu.m apart and containing a layer of a liquid crystal material. Electrode structures on the inner face of the glass slides enable an electric field to be applied across the liquid crystal layer. Application of an appropriate voltage causes a molecular re-alignment of the liquid crystal molecules. This cell ON-state is visibly different from the zero voltage cell OFF-state and forms the basis for different types of displays.
Car mirrors are known that "dip" to reduce their reflectance during night time driving. Such mirrors utilize a movable wedge. Dipping mirrors incorporating liquid crystal displays have been made using negative dielectric anisotropy material in a dynamic scattering mode. This liquid crystal material can adopt two states; a clear transparent cell OFF-state and a light scattering cell ON-state. In the OFF-state light is reflected off a mirror behind the cell. In the ON-state a much smaller amount of light is reflected off the cell front surface. This known driving mirror has disadvantages in that the liquid crystal material has insufficient chemical stability and operating temperature range. As a result it is difficult and expensive to make.